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<div class="titlepage"><div><div><h3 class="title">
<a name="asio.overview.signals"></a><a class="link" href="signals.html" title="Signal Handling">Signal Handling</a>
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<p>
        Asio supports signal handling using a class called <a class="link" href="../reference/signal_set.html" title="signal_set">signal_set</a>.
        Programs may add one or more signals to the set, and then perform an <code class="computeroutput">async_wait()</code>
        operation. The specified handler will be called when one of the signals occurs.
        The same signal number may be registered with multiple <a class="link" href="../reference/signal_set.html" title="signal_set">signal_set</a>
        objects, however the signal number must be used only with Asio.
      </p>
<pre class="programlisting">void handler(
    const asio::error_code&amp; error,
    int signal_number)
{
  if (!error)
  {
    // A signal occurred.
  }
}

...

// Construct a signal set registered for process termination.
asio::signal_set signals(io_context, SIGINT, SIGTERM);

// Start an asynchronous wait for one of the signals to occur.
signals.async_wait(handler);
</pre>
<p>
        Signal handling also works on Windows, as the Microsoft Visual C++ runtime
        library maps console events like Ctrl+C to the equivalent signal.
      </p>
<h5>
<a name="asio.overview.signals.h0"></a>
        <span><a name="asio.overview.signals.see_also"></a></span><a class="link" href="signals.html#asio.overview.signals.see_also">See
        Also</a>
      </h5>
<p>
        <a class="link" href="../reference/signal_set.html" title="signal_set">signal_set</a>, <a class="link" href="../examples/cpp03_examples.html#asio.examples.cpp03_examples.http_server">HTTP
        server example (C++03)</a>, <a class="link" href="../examples/cpp11_examples.html#asio.examples.cpp11_examples.http_server">HTTP
        server example (C++11)</a>.
      </p>
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<td align="right"><div class="copyright-footer">Copyright &#169; 2003-2018 Christopher M. Kohlhoff<p>
        Distributed under the Boost Software License, Version 1.0. (See accompanying
        file LICENSE_1_0.txt or copy at <a href="http://www.boost.org/LICENSE_1_0.txt" target="_top">http://www.boost.org/LICENSE_1_0.txt</a>)
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